Thermal imaging aids compressor development

A UK-based engineering firm is using thermal imaging cameras from Micro-Epsilon to accurately measure the temperature profile of its new air compressor, which is already attracting worldwide attention due to its energy saving capabilities.

Based in Napton, Warwickshire, Lontra is an engineering company that delivers innovative air compressor designs, proven to provide real energy and cost savings to industry.

Advanced testing facilities at Lontra enable the company to control and accurately measure the true performance of its products, namely the Blade Compressor. This new form of air compressor (or vacuum pump) is the first widely applicable new compressor design in the industry for over 80 years. Founder and CEO of Lontra, Steve Lindsey, was recently shortlisted in the 2017 European Inventor Awards (run by the European Patent Office) and was the only UK finalist in these prestigious Awards.

Carl Godden, Senior Development Engineer at Lontra states: “The Blade Compressor takes a clean-sheet approach by solving the problems associated with traditional compressor designs. The compressor itself is a circular mechanism, replacing the old ‘up and down’ piston technology, therefore compressing air in front and inducing the air behind in continuous motion. As a result, this minimises waste and provides the industry with a triple benefit: it’s oil-free, approximately 21 per cent more energy efficient than current machines and is more reliable.”

Thermal monitoring of development machines

In 2015, when the initial Blade Compressor prototypes were being developed, Carl Godden required some thermal imaging cameras to measure the external skin temperatures of the complete compressor, as well as its various sub-assemblies and individual components such as bearings. Clearances inside the compressor are very tight so it’s important to monitor the temperature profile of abradable coatings on some of the internal components during tests.

Prior to purchasing two thermal imaging cameras from Micro-Epsilon in Spring 2015, Godden says that all surface temperature measurements on compressors and their various sub-assemblies were performed using stick-on thermocouples. At least 15 thermocouples were required to do this, with each thermocouple requiring its own separate measurement channel to record the temperatures at various locations on the compressor.

“The other problem with this approach is that you obtain spot temperatures from the various thermocouple positions, but you don’t get an overall temperature profile or video snapshot of the complete compressor or surface area. In addition, we started to work on a more compact, higher pressure version of the Blade Compressor. We needed to measure the temperature profile of this new design and monitor the temperature differences across various components and coatings so we started to look for a suitable thermal imaging camera,” explains Godden.

IR thermal imaging

After considering various suppliers, Godden selected the thermoIMAGER TIM 640, an infrared thermal imaging camera from Micro-Epsilon that is able to record radiometric video at an optical resolution of 640×480 pixels. With extremely compact dimensions of 45x56x90mm and a weight of just 320g, compared to other similar-size cameras, the thermoIMAGER TIM 640 is the only camera that enables the recording of radiometric video images at 32Hz and a VGA resolution of 640×480 pixels.

Godden continues: “We have three soundproofed test cells where we perform all our R&D work on our prototype and development compressors. The two larger test cells we have are for the testing of complete compressors and the third cell is used for rig work, in other words, testing of coatings, gearboxes, oil handling and so on. The two Micro-Epsilon thermal imaging cameras can be transferred into any of the test cells and used to monitor surface temperatures in areas that may be of interest to us.”

“We also monitor displacements, pressures, flows and temperatures to keep an eye on things on our own in house-developed DAQ system. Using high-speed pressure transducers, we can also measure any internal pressure pulsations and analyse to see if they have any negative or beneficial impact on compressor efficiency. We can then investigate ways and means to lessen or utilise this further through additional development.”

thermoIMAGER TIM 640

With a thermal sensitivity of 75mK, the camera can detect very small temperature differences. At ambient temperatures of between 0 and 50°C, the camera can measure object temperatures ranging from -20°C to +900°C.

By using thermal imaging cameras – in R&D, new product development and high volume production – hot spots and defects can be detected quickly and reliably, without influencing the target object. A USB 2.0 interface allows video recording at 32Hz. This is beneficial for short-term thermal measurement activities, which need to be analysed in slow motion playback. Individual snapshots can be taken from these recordings. Measurement points are freely selectable and can be analysed via user-defined areas of interest. Alarms can also be set up and displayed, as well as maximum, minimum and average temperatures.

Easy integration

For easy process integration, the TIM 640 is supplied with the TIM Connect software as standard. This enables users to monitor and document measurements and to edit infrared video images. The software provides quick and easy set up together with a range of software tools that enable the cameras to be used in R&D tasks as well as process control.

“We’ve had no issues at all with the thermal imaging cameras,” reports Godden. “They’ve been very reliable, easy to set up and use, with little training required. We also particularly like the TIM CONNECT software supplied with the camera, as this has enabled us to more easily integrate the cameras with our own DAQ systems. It’s all very flexible and allows us to share temperature profile data and temperature snapshots with our analysis team, who can then check how closely our compressor design models and simulations match the real thing, i.e. the actual recorded temperature measurements of the compressor prototypes in the test cells. Also, the camera heads are extremely compact on the TIM 640 compared to other cameras currently available in the market. This allows us to record measurements with the cameras in very tight, restricted spaces.”

The TIM 640 is also supplied with an integral process interface for input and output of analogue and digital signals (alarms, temperature values, etc.). Open connectivity drivers are also provided for software integration via DLL, ComPort and LabVIEW, simplifying connectivity to fieldbus networks and automation systems.